JP2000232744A - Rotor shape and shaft press-fit structure of SR motor - Google Patents

Abstract

(57) [Problem] To improve the concentricity between the outer periphery of a rotor core and the center of a shaft, and to transmit necessary torque from the rotor to the shaft. SOLUTION: A protrusion 22 is formed along an axial direction on an inner peripheral surface of a hole 21 of a rotor core 2 into which a shaft 3 is press-fitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner rotor of an SR motor in which a shaft is press-fitted into a center portion of a rotor core, and more particularly to a rotor of an SR motor capable of increasing concentricity between the outer periphery of the rotor and the center of the shaft. The present invention relates to a shape and a shaft press-fitting structure.

[0002]

2. Description of the Related Art As shown in FIG. 4, in an inner rotor of an SR motor, a hole 101 for press-fitting is formed at the center of a rotor core 100, and the hole 1 for press-fitting is formed.
A shaft 102 serving as a rotation axis of the rotor is inserted into the shaft 01.

In general, the hole of the rotor core is formed in a circular shape, for example, a perfect circle, and a shaft having a smaller outer diameter than the hole of the rotor core is used. Further, in order to fix the shaft and the rotor, for example, the outer diameter of the shaft is subjected to processing such as staking or howling or knurling to provide fine projections of several tens to several hundreds μm. .

[0004]

However, the inner diameter of the rotor core is difficult to achieve concentricity and roundness with the outer diameter of the rotor, and the precision can be increased if the die to be drilled is improved, but the cost increases. Leads to. Therefore, it is difficult to increase the accuracy of the concentricity between the outer periphery of the rotor core and the center of the shaft press-fitted into the hole of the rotor core.
In order to increase this accuracy, for example, in order to increase the concentricity between the outer diameter of the shaft and the outer diameter of the rotor, it is necessary to deform the inner diameter of the rotor core and follow the outer diameter of the shaft.

As a result, the following problems are caused. That is, the frictional force between the rotor core and the shaft increases,
The shaft is bent at the time of press-fitting, the inner diameter of the hole in the rotor core follows the shaft as it is, and the roundness and concentricity of the rotor core vary in the outer diameter dimension, and the concentricity between the shaft center and the outer periphery of the rotor core is accurate. Worse.

In view of the above circumstances, the present invention can increase the concentricity between the outer periphery of the rotor core and the center of the shaft, and can transmit the necessary torque from the rotor to the shaft. It is an object to provide a shaft press-fitting structure.

[0007]

According to a first aspect of the present invention, an inner peripheral surface of a hole into which a shaft of a rotor core is press-fitted is provided in an inner rotor of an SR motor in which a shaft is press-fitted into a center portion of a rotor core. A projection and a stripe are formed along the axial direction.

[0008]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a rotor shape of an SR motor according to the present invention.
In the inner rotor 1, a projection 2 is formed on the inner peripheral surface of a hole 21 provided at the center of the rotor core 2 in parallel with the central axis direction.
2 are formed, and the press-fitted shaft 3 is formed in a straight rod shape without providing a conventional projection.

The rotor core 2 is formed of a silicon steel plate, and several (in this embodiment, four, but not limited thereto) teeth 23 are formed on the outer periphery of the rotor core 2. The hole 21 formed in the center of the rotor core 2 is formed in a circular cross section (especially, in this embodiment, a perfect circle), but the protrusion 22 has an inner periphery corresponding to the position where each taste 23 is formed. In the surface part (the tip part narrows), it protrudes in a substantially mountain shape,
As shown in FIG. 2, the projecting amount h is formed to have a size larger than the difference between the inner diameter R1 of the rotor core 2 and the outer diameter R2 of the shaft 3. The shape of the projection is not particularly limited to that of this embodiment, and the number and position are not limited to those of this embodiment.

The shaft 3 is different from the conventional one, as shown in FIG.
As shown in (1), it is made of a straight rod, and no fine protrusions (irregularities) are formed on the outer peripheral surface. The shaft 3 of this embodiment uses a silicon steel plate, and is quenched and tempered to increase rigidity at least as compared with the rotor core 2.

The gap between the rotor core 2 and the shaft 3 press-fitted into the hole 21 of the rotor core 2 may be kept press-fitted depending on the use conditions, but if the load is large, the shaft 3 is press-fitted. Later, an appropriate mold resin (or an appropriate mixture of metal powder and resin) 4 or an adhesive may be filled to further increase the rigidity and integration of the rotor core 2 and the shaft 3.

Therefore, according to this embodiment, the shaft 3 having a high rigidity is press-fitted into the hole of the rotor core 2 having a lower rigidity.
1 (formed in parallel with the axial direction of the rotor core 2) is guided by the projections 22 (shown by hatching in FIG. 22 can be press-fitted in parallel with the axial direction of the rotor core 2. Further, in this embodiment, a gap formed between the hole of the rotor core 2 and the shaft 3 is thereafter filled and cured with a suitable resin (in this case, metal powder may be mixed with the resin) 4. , So that both are more firmly integrated.

As a result, the shaft 3 is reliably and smoothly moved in a predetermined direction without causing a slight bending or the like of the shaft 3 due to frictional force, and high concentric accuracy is secured between the outer periphery of the rotor core 2 and the axis of the shaft 3. Shaft 3
Insertion can be realized.

[0014]

As described above, according to the present invention, the SR is formed by press-fitting the shaft into the center of the rotor core.
In the inner rotor of the motor, the inner circumference of the hole into which the shaft of the rotor core is press-fitted is formed with protrusions and stripes along the axial direction, so that when the shaft is pressed into the rotor core, the friction acting on the shaft in an irregular direction Since it can prevent bending in irregular directions with force,
The concentricity between the outer peripheral surface of the rotor core and the shaft of the shaft can be secured with high accuracy. In addition, according to the present invention, the hard shaft side is press-fitted into the hole of the rotor core having a lower hardness, so that a part of the projections and the streaks formed in this hole are press-fitted and assembled while being shaved off by the hard shaft. Therefore, the shaft and the rotor core are firmly and integrally fixed (via the press-contacted protrusions and stripes), so that the rotational force of the rotor core can be reliably transmitted to the shaft.

[Brief description of the drawings]

FIG. 1 is a plan view showing a rotor shape of an SR motor according to the present invention.

FIG. 2 is an enlarged view of a main part.

FIG. 3 is a perspective view showing a state of the rotor according to the present invention before the shaft is press-fitted.

FIG. 4 is a perspective view showing a state before press-fitting a shaft of a conventional rotor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner rotor 2 Rotor core 21 Hole 22 Projection 3 Shaft 4 Resin

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroyuki Shimizu 1-19-9 Tsutsumori, Sumida-ku, Tokyo Nippon Electric Seiki Co., Ltd. F-term (reference) 5H002 AA07 AA08 AB07 AB08 AC06 AE08 5H615 AA01 BB01 BB07 BB14 PP02 PP06 PP07 PP24 SS05 SS18 SS19

Claims (4)

[Claims] 1. An inner rotor of an SR motor in which a shaft is press-fitted into a central portion of a rotor core, wherein a protrusion or a streak is formed along an axial direction on an inner peripheral surface of a hole into which the shaft of the rotor core is press-fitted. Shape and shaft press-fit structure of SR motor. 2. A gap between an outer peripheral surface of a shaft formed at the time of press-fitting and an inner peripheral surface of a rotor core hole is filled and filled with a molding agent or an adhesive made of resin or resin and metal powder. The rotor shape of the SR motor according to claim 1. 3. The rotor shape of an SR motor according to claim 1, wherein projections and stripes formed on the inner periphery of the hole of the rotor core are provided at least at portions corresponding to the teeth projecting from the outer periphery. 4. The shaft is press-fitted while shaving off a projection or a streak provided in a hole of a rotor core at the time of press-fitting of the shaft, thereby absorbing an error that has occurred during machining or an error that may occur at the time of press-fitting and assembling. 2. The shaft press-fitting structure for an SR motor according to claim 1, wherein the shaft is press-fitted.